Throughout the period of sleep, humans typically experience dream periods. Dream periods (REM) comprise approximately 15%-20% of the evenings sleep and occur with regularity every 80-100 minutes. While the subject is asleep, however, the body continues to exhibit many characteristic physiological changes. Although most of these changes are readily monitored and calibrated, the preferred embodiment focuses on the subject's motor activity which occurs during sleep. For instance, during sleep there are frequent gross body movements or postural changes. These shifts in position occur with increased frequency before and after dream periods, whereas a period of simulated paralysis occurs during the dream period proper. As a specific example, during human sleep there is a period of increased motor activity before a dream, a period of relative immobility during the dream, and increased motor activity following the dream. This behavior is then repeated 80-100 minutes later. Prior art, such as Ethology of Sleep Studied with Time-Lapse Photography: Postural Immobility and Sleep-Cycle Phase in Humans" by Hobson in Science, Vol. 201, 1978, pp 1251-1253, includes the analysis of postural changes during sleep and acknowledges the regularity of dreaming but, never has a means for the utilization and calibration of gross body movements in predicting dream occurrences been disclosed. This is also discussed in Advances in Dream Research by Elliot Weitzman, Spectrum Publications, 1976.
During an average sleeping period, the sleep-dream cycle repeats 4-6 times as noted in "Every 90 Minutes, A Brainstorm" by Michael H. Chase, Psychology Today, November, 1979, p. 172. The percentage of dreams recalled and the accuracy with which they are recalled varies between individuals but, dream content is usually forgotten unless the individual has been awakened or disturbed during the dream. To effectively capture dream content it is therefore desirable to awaken a subject at the conclusion of his dream as recognized in Sleep and Dreaming by David B. Cohen, A. Wheaton ad Co., Ltd., 1979.
Many prior patents have been obtained for the awakening of a subject in response to the monitoring of brain wave activity which would indicate that a subject is falling asleep. These systems have obvious use in the awakening of a dozing driver or the monitoring of patients in an intensive care situation. U.S. Pat. No. 4,228,806 discloses a device which inhibits wake-up alarms during deeper phases of sleep; thus functioning as an alarm clock accessory which prevents the subject from being aroused from a deep sleep. There is no attempt, however, in these prior art arrangements to address dream retrieval or a means of automated calibration or correlation of gross body movements found near and about dream periods.
Obvious to those of the field is the possible alteration of dream content by the introduction of physical stimuli to a dreaming individual. Prior art includes devices which dictate suggestions to sleeping individuals at some predetermined time into the period of sleep. However, these devices do not calculate when the subject is dreaming and only provide for random application of subject stimuli. See for example "Lucid Dreaming" by Stephen LaBerge in Psychology Today, January, 1981, pp. 48-57.
British Patent No. 1,215,904 and U.S. Pat. No. 4,420,011 disclose devices which measure increased respiration during "unpleasant dreams," after which, an attempt is made to bring the subject to a higher level of consciousness where they might experience a more "lucid" dream. These references lack the correlation of findings from earlier in the sleeping period to more recent subject behavior in the predicting and ultimate retrieval of their dreams.
Motion sensors function in various sytems and devices not related to human movement. U.S. Pat. Nos. 4,381,504 and 4,450,326, both disclose devices which establish electrical continuity across two or more terminals when translated or displaced. However, neither of these embodiments measure or correlate the intensity of sound produced during the actual motion. U.S. Pat. No. 3,955,562 depicts a device for measuring the degree of positional change found in normal human movement but pertains only to the connection of electrical contacts by the depression of switches or translation of electrically conductive fluid.